1. Field of the Invention
The present invention relates generally to union apparatus for joining fluid-handling lines, and more particularly to an improved fluid flow-line coupling device having double sealing and leak trace capability.
2. Brief Description of the Prior Art
While pipeline union couplers and other couplers associated with filters, pumps, valves, etc., have long been used in water lines, fuel lines, chemical supply lines, etc., such couplers have typically depended upon the clamping together of either two planar or frusto-conically configured annular surfaces with or without O-rings. Such unions, however, are subject to leakage if not tightly clamped together or if the O-rings either have failed or lost their resiliency. Moreover, resilient O-rings can leach out in certain chemicals. For applications in which leak detection is required, a dual O-ring configuration having an intermediate groove and leak trace has been used. One such embodiment is disclosed in U.S. Pat. No. 5,090,871 issued to Carl E. Story and Kenneth M. O'Connor entitled "Junction Assembly With Leak Detection Means." While such dual O-ring structure was suitable for many applications, the dependency upon O-ring integrity and clamping force uniformity left room for improvement. One such improvement is disclosed in my co-pending application entitled "FLOW-THROUGH, IN-LINE FILTER HOUSING" (Ser. No. 08/276,925 filed Jul. 19, 1994 now U.S. Pat. No. 5,482,618) in which it is disclosed that, as an alternative to using O-rings, one can provide one or more tapered annular grooves on the face of one coupling part and either affix to, or make integral with, an opposing face of another part, an outwardly projecting rib or ridge of either rigid, resilient or deformable material which will mate with the annular groove and provide a reliable sealing mechanism between two fluid flow-line junction elements.